Automated GitHub upload script

@financeCoding This should be working to upload/update the repositories on either your personal account or an organization where you have the permission.

tool/update.sh <yourUserName>
or
tool/update.sh <yourUserName> <OrgName>

I've limited the output to 5 APIs for testing, uncomment the according lines at the bottom of the script to do the same.

These are the libraries that I automatically created and pushed to GitHub for testing:
https://github.com/Scarygami/dart_adsense_v1_1_api_client
https://github.com/Scarygami/dart_adsense_v1_api_client
https://github.com/Scarygami/dart_adexchangeseller_v1_api_client
https://github.com/Scarygami/dart_adexchangebuyer_v1_1_api_client
https://github.com/Scarygami/dart_adexchangebuyer_v1_api_client

Checking for changes works as well with the changes in the Generator, so updates are only pushed (including an increase in the version build number) if there really were changes.

Updates are also pushed if we increase the major.minor clientVersion in the generator.

Adding a final "pub publish" to the script will be the logical next step of course :)